55 lines
1.3 KiB
Go
55 lines
1.3 KiB
Go
// Copyright ©2015 The Gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package gonum
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import (
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"gonum.org/v1/gonum/blas"
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"gonum.org/v1/gonum/blas/blas64"
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)
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// Dtrtrs solves a triangular system of the form A * X = B or A^T * X = B. Dtrtrs
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// returns whether the solve completed successfully. If A is singular, no solve is performed.
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func (impl Implementation) Dtrtrs(uplo blas.Uplo, trans blas.Transpose, diag blas.Diag, n, nrhs int, a []float64, lda int, b []float64, ldb int) (ok bool) {
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switch {
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case uplo != blas.Upper && uplo != blas.Lower:
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panic(badUplo)
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case trans != blas.NoTrans && trans != blas.Trans && trans != blas.ConjTrans:
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panic(badTrans)
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case diag != blas.NonUnit && diag != blas.Unit:
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panic(badDiag)
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case n < 0:
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panic(nLT0)
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case nrhs < 0:
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panic(nrhsLT0)
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case lda < max(1, n):
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panic(badLdA)
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case ldb < max(1, nrhs):
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panic(badLdB)
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}
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if n == 0 {
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return true
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}
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switch {
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case len(a) < (n-1)*lda+n:
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panic(shortA)
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case len(b) < (n-1)*ldb+nrhs:
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panic(shortB)
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}
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// Check for singularity.
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nounit := diag == blas.NonUnit
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if nounit {
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for i := 0; i < n; i++ {
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if a[i*lda+i] == 0 {
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return false
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}
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}
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}
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bi := blas64.Implementation()
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bi.Dtrsm(blas.Left, uplo, trans, diag, n, nrhs, 1, a, lda, b, ldb)
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return true
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}
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